31720721480 has 256 divisors, whose sum is σ = 86084812800. Its totient is φ = 10292106240.

The previous prime is 31720721477. The next prime is 31720721497. The reversal of 31720721480 is 8412702713.

It is a Harshad number since it is a multiple of its sum of digits (35).

It is a self number, because there is not a number n which added to its sum of digits gives 31720721480.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 114515102 + ... + 114515378.

It is an arithmetic number, because the mean of its divisors is an integer number (336268800).

Almost surely, 2^31720721480 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 31720721480, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43042406400).

31720721480 is an abundant number, since it is smaller than the sum of its proper divisors (54364091320).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

31720721480 is a wasteful number, since it uses less digits than its factorization.

31720721480 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 572 (or 568 counting only the distinct ones).

The product of its (nonzero) digits is 18816, while the sum is 35.

The spelling of 31720721480 in words is "thirty-one billion, seven hundred twenty million, seven hundred twenty-one thousand, four hundred eighty".